A network system such as a data center network or the like includes multiple servers to which a virtual machine (Virtual Machine, hereafter also referred to as VM) is provided, and multiple switch devices. With such a network system, in the event that a certain VM has been moved from a server to which the VM thereof has belonged so far to another server by live migration (Live Migration), the servers and switch devices making up the net work have to newly establish a communication path as to the VM after movement.
Therefore, the servers and switch devices transmit an ARP (Address Resolution Protocol) request to the moved VM. This ARP request is transmitted to the entire network to which the server belongs to which the VM after movement belongs, using broadcasting. When receiving an ARP request, the server to which the VM after movement belongs transmits an ARP response based on a MAC (Media Access Control) address of the VM thereof.
The servers and switch devices learn, according to reception of the ARP response, a correspondence relation between a MAC address included the ARP response and output interface of the own device in an autonomic dispersive manner to obtain setting information (forwarding information) regarding the VM after movement. Hereafter, with regard to a node device such as a VM or the like, learning of a correspondence relation between a MAC address thereof and the output interface of the own device may simply be referred to as MAC address learning. The servers and switch devices perform MAC address learning regarding the moved VM, thereby updating a forwarding information table in which forwarding information (setting information) of traffic data is stored.
Also, as a technique to update setting information at a switch device when a VM is moved by live migration, a technique called AMPP (Automatic Migration of Port Profile) has been widely recognized. The AMPP is a protocol formulated by IEEE (IEEE 802.IQbg). According to the AMPP, in response to movement of a VM by live migration, a port profile (setting information) within a switch device on the lowest stage coupled to a movement source server of the VM is moved to a switch device on the lowest stage coupled to a movement destination server.
FIG. 1 is a diagram for describing operation of the AMPP.
As illustrated in FIG. 1, with an L2 (layer 2) network system 100, servers 102-1 and 102-2 are coupled to an L2 switch network 106 via corresponding switch devices 104-1 and 104-2, respectively. The server 102-1 includes a VM 112-1 (before movement by live migration), a VM 112-2, and a virtual switch 114-1, and the server 102-2 includes a VM 112-1 (after movement by live migration), a VM 112-3, and a virtual switch 114-2. Each of the VMs 112-1 to 112-3 is coupled to the corresponding switch device 104-1/104-2 via the corresponding virtual switch 114-1/114-2.
The switch devices 104-1 and 104-2 are, of switch devices having a multi-stage configuration making up the network system 100, physical switches positioned on the lowest stage which may be coupled to the servers 102-1 and 102-2 without passing through another switch device, respectively. Each of the switch devices 104-1 and 104-2 internally includes a port profile (setting information). The port profile indicates a correspondence relation between a MAC address assigned to each of the VMs and an output port (output interface) of the own device.
As illustrated in FIG. 1, with an example wherein the VM 112-1 belonging to the server 102-1 has been moved to the other server 102-2 by live migration, in response to the VM 112-1 moving from the server 102-1 to the server 102-2, a port profile 116 within the switch device 104-1 on the lowest stage coupled to the server 102-1 is moved to the switch device 104-2 on the lowest stage coupled to the server 102-2.
The switch devices 104-1 and 104-2 on the lowest stage perform MAC address learning regarding the VM after movement according to movement of the port profile (setting information) by the AMPP, and update the forwarding information table in which forwarding information (setting information) of traffic data is stored.
On the other hand, switch devices other than the lowest stage (multiple switch devices making up the L2 switch network) execute, as described above, according to reception of an ARP response, MAC address learning regarding the moved VM, thereby updating the forwarding information table.
Note that a technique has been described in Japanese Laid-open Patent Publication No. 2010-124129 wherein, in the event of moving a VM, a MAC address of the VM to be moved is assigned to a physical interface of a movement destination server, and the switches making up a network are made to learn the assigned MAC address prior to movement of the VM.